My son had his two month old shots yesterday he fell asleep at eight at 8 o'clock is still sound…

My son had his two month old shots yesterday he fell asleep at eight at 8 o'clock is still sound asleep and I'm going on eight hours I know everyone says babies will wake up when they're hungry but has anyone else had a two-month-old or around his age sleep for over eight hours without eating how many hours could he go and when should I start to worry???